An alkaline dry cell has a large capacity, and from which a large electric current can be taken out. Therefore, the alkaline dry cell is widely used. In view of increasing a capacity, it is considered to be advantageous to reduce a thickness of a cell case (in particular, a body portion of the cell case) that does not contribute to capacity of an alkaline dry cell.
A positive electrode of an alkaline dry cell is made of a pellet including manganese dioxide powder as a positive electrode active material and graphite powder as a conductive agent. In an alkaline dry cell, manganese dioxide expands during discharging, so that a positive electrode as a whole expands.
Patent Literature (PTL) 1 proposes that in an alkaline dry cell in which the body portion of the cell case has a thickness in a range from 0.1 to 0.17 mm, the density of graphite in the positive electrode material is adjusted in order to suppress increase in the dimension of the outer diameter of the cell after discharging while high capacity is secured. In PTL 1, stress caused by the expansion of manganese dioxide is allowed to diffuse by setting the density of graphite to a specific range.
On the other hand, in PTL 2, in order to enhance the discharging performance of an alkaline dry cell, a packing density of manganese dioxide in a positive electrode and a packing density of zinc in the negative electrode are adjusted, and at the same time, the relation between these packing densities and thicknesses in the diameter direction of the positive electrode and the negative electrode is adjusted.